1. Field of the Invention
The present invention relates to a position-detecting system that detects a position of an object moving two dimensionally. Particularly, the invention relates to a position-detecting system that is provided as an element of an anti-shake device of a digital camera, and which detects a relative position of an imaging device with respect to an optical axis of a photographing lens.
2. Description of the Related Art
Conventionally, anti-shake devices (camera-shake compensation devices) are used in the digital camera field. An anti-shake device prevents or compensates for image blur produced on an imaging surface of an imaging device. This is achieved by moving a camera-shake compensation lens or the imaging device along a plane perpendicular to the optical axis of the photographing lens to counteract the camera-shake, which is induced during photographing. The anti-shake device is provided with a position-sensing system to detect a relative position of the imaging device with respect to the optical axis of the photographing lens (refer to Japanese unexamined patent publication No. 2001-117129). In this type of position sensing system, a two-dimensional position-sensing device (PSD) receives a spotlight emitted from a light source (LED), and thereby the relative position is detected in accordance with a position where the spotlight is received. Specifically, the two-dimensional position-sensing device (PSD) and the light source (LED) are provided on a fixed member and a moving member. The relative position of the moving member with respect to the fixed member is detected by detecting the position of the light which is made incident to the two-dimensional position-sensing device, so that the movement of the moving member or an object is detected.